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+/**
+ * @file rtems/score/cpu.h
+ */
+
+/*
+ * This include file contains information pertaining to the Hitachi SH
+ * processor.
+ *
+ * Authors: Ralf Corsepius (corsepiu@faw.uni-ulm.de) and
+ * Bernd Becker (becker@faw.uni-ulm.de)
+ *
+ * COPYRIGHT (c) 1997-1998, FAW Ulm, Germany
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ *
+ * COPYRIGHT (c) 1998-2006.
+ * On-Line Applications Research Corporation (OAR).
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.com/license/LICENSE.
+ *
+ * $Id$
+ */
+
+#ifndef _RTEMS_SCORE_CPU_H
+#define _RTEMS_SCORE_CPU_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <rtems/score/types.h>
+#include <rtems/score/sh.h>
+
+/* conditional compilation parameters */
+
+/*
+ * Should the calls to _Thread_Enable_dispatch be inlined?
+ *
+ * If TRUE, then they are inlined.
+ * If FALSE, then a subroutine call is made.
+ *
+ * Basically this is an example of the classic trade-off of size
+ * versus speed. Inlining the call (TRUE) typically increases the
+ * size of RTEMS while speeding up the enabling of dispatching.
+ * [NOTE: In general, the _Thread_Dispatch_disable_level will
+ * only be 0 or 1 unless you are in an interrupt handler and that
+ * interrupt handler invokes the executive.] When not inlined
+ * something calls _Thread_Enable_dispatch which in turns calls
+ * _Thread_Dispatch. If the enable dispatch is inlined, then
+ * one subroutine call is avoided entirely.]
+ */
+
+#define CPU_INLINE_ENABLE_DISPATCH FALSE
+
+/*
+ * Should the body of the search loops in _Thread_queue_Enqueue_priority
+ * be unrolled one time? In unrolled each iteration of the loop examines
+ * two "nodes" on the chain being searched. Otherwise, only one node
+ * is examined per iteration.
+ *
+ * If TRUE, then the loops are unrolled.
+ * If FALSE, then the loops are not unrolled.
+ *
+ * The primary factor in making this decision is the cost of disabling
+ * and enabling interrupts (_ISR_Flash) versus the cost of rest of the
+ * body of the loop. On some CPUs, the flash is more expensive than
+ * one iteration of the loop body. In this case, it might be desirable
+ * to unroll the loop. It is important to note that on some CPUs, this
+ * code is the longest interrupt disable period in RTEMS. So it is
+ * necessary to strike a balance when setting this parameter.
+ */
+
+#define CPU_UNROLL_ENQUEUE_PRIORITY TRUE
+
+/*
+ * Does the CPU follow the simple vectored interrupt model?
+ *
+ * If TRUE, then RTEMS allocates the vector table it internally manages.
+ * If FALSE, then the BSP is assumed to allocate and manage the vector
+ * table
+ *
+ * SH Specific Information:
+ *
+ * XXX document implementation including references if appropriate
+ */
+#define CPU_SIMPLE_VECTORED_INTERRUPTS TRUE
+
+/*
+ * Does RTEMS manage a dedicated interrupt stack in software?
+ *
+ * If TRUE, then a stack is allocated in _ISR_Handler_initialization.
+ * If FALSE, nothing is done.
+ *
+ * If the CPU supports a dedicated interrupt stack in hardware,
+ * then it is generally the responsibility of the BSP to allocate it
+ * and set it up.
+ *
+ * If the CPU does not support a dedicated interrupt stack, then
+ * the porter has two options: (1) execute interrupts on the
+ * stack of the interrupted task, and (2) have RTEMS manage a dedicated
+ * interrupt stack.
+ *
+ * If this is TRUE, CPU_ALLOCATE_INTERRUPT_STACK should also be TRUE.
+ *
+ * Only one of CPU_HAS_SOFTWARE_INTERRUPT_STACK and
+ * CPU_HAS_HARDWARE_INTERRUPT_STACK should be set to TRUE. It is
+ * possible that both are FALSE for a particular CPU. Although it
+ * is unclear what that would imply about the interrupt processing
+ * procedure on that CPU.
+ */
+
+#define CPU_HAS_SOFTWARE_INTERRUPT_STACK TRUE
+#define CPU_HAS_HARDWARE_INTERRUPT_STACK FALSE
+
+/*
+ * We define the interrupt stack in the linker script
+ */
+#define CPU_ALLOCATE_INTERRUPT_STACK FALSE
+
+/*
+ * Does the RTEMS invoke the user's ISR with the vector number and
+ * a pointer to the saved interrupt frame (1) or just the vector
+ * number (0)?
+ */
+
+#define CPU_ISR_PASSES_FRAME_POINTER 0
+
+/*
+ * Does the CPU have hardware floating point?
+ *
+ * If TRUE, then the RTEMS_FLOATING_POINT task attribute is supported.
+ * If FALSE, then the RTEMS_FLOATING_POINT task attribute is ignored.
+ *
+ * We currently support sh1 only, which has no FPU, other SHes have an FPU
+ *
+ * The macro name "SH_HAS_FPU" should be made CPU specific.
+ * It indicates whether or not this CPU model has FP support. For
+ * example, it would be possible to have an i386_nofp CPU model
+ * which set this to false to indicate that you have an i386 without
+ * an i387 and wish to leave floating point support out of RTEMS.
+ */
+
+#if SH_HAS_FPU
+#define CPU_HARDWARE_FP TRUE
+#define CPU_SOFTWARE_FP FALSE
+#else
+#define CPU_SOFTWARE_FP FALSE
+#define CPU_HARDWARE_FP FALSE
+#endif
+
+/*
+ * Are all tasks RTEMS_FLOATING_POINT tasks implicitly?
+ *
+ * If TRUE, then the RTEMS_FLOATING_POINT task attribute is assumed.
+ * If FALSE, then the RTEMS_FLOATING_POINT task attribute is followed.
+ *
+ * If CPU_HARDWARE_FP is FALSE, then this should be FALSE as well.
+ */
+
+#if SH_HAS_FPU
+#define CPU_ALL_TASKS_ARE_FP TRUE
+#else
+#define CPU_ALL_TASKS_ARE_FP FALSE
+#endif
+
+/*
+ * Should the IDLE task have a floating point context?
+ *
+ * If TRUE, then the IDLE task is created as a RTEMS_FLOATING_POINT task
+ * and it has a floating point context which is switched in and out.
+ * If FALSE, then the IDLE task does not have a floating point context.
+ *
+ * Setting this to TRUE negatively impacts the time required to preempt
+ * the IDLE task from an interrupt because the floating point context
+ * must be saved as part of the preemption.
+ */
+
+#if SH_HAS_FPU
+#define CPU_IDLE_TASK_IS_FP TRUE
+#else
+#define CPU_IDLE_TASK_IS_FP FALSE
+#endif
+
+/*
+ * Should the saving of the floating point registers be deferred
+ * until a context switch is made to another different floating point
+ * task?
+ *
+ * If TRUE, then the floating point context will not be stored until
+ * necessary. It will remain in the floating point registers and not
+ * disturned until another floating point task is switched to.
+ *
+ * If FALSE, then the floating point context is saved when a floating
+ * point task is switched out and restored when the next floating point
+ * task is restored. The state of the floating point registers between
+ * those two operations is not specified.
+ *
+ * If the floating point context does NOT have to be saved as part of
+ * interrupt dispatching, then it should be safe to set this to TRUE.
+ *
+ * Setting this flag to TRUE results in using a different algorithm
+ * for deciding when to save and restore the floating point context.
+ * The deferred FP switch algorithm minimizes the number of times
+ * the FP context is saved and restored. The FP context is not saved
+ * until a context switch is made to another, different FP task.
+ * Thus in a system with only one FP task, the FP context will never
+ * be saved or restored.
+ */
+
+#if SH_HAS_FPU
+#define CPU_USE_DEFERRED_FP_SWITCH FALSE
+#else
+#define CPU_USE_DEFERRED_FP_SWITCH TRUE
+#endif
+
+/*
+ * Does this port provide a CPU dependent IDLE task implementation?
+ *
+ * If TRUE, then the routine _CPU_Thread_Idle_body
+ * must be provided and is the default IDLE thread body instead of
+ * _CPU_Thread_Idle_body.
+ *
+ * If FALSE, then use the generic IDLE thread body if the BSP does
+ * not provide one.
+ *
+ * This is intended to allow for supporting processors which have
+ * a low power or idle mode. When the IDLE thread is executed, then
+ * the CPU can be powered down.
+ *
+ * The order of precedence for selecting the IDLE thread body is:
+ *
+ * 1. BSP provided
+ * 2. CPU dependent (if provided)
+ * 3. generic (if no BSP and no CPU dependent)
+ */
+
+#define CPU_PROVIDES_IDLE_THREAD_BODY TRUE
+
+/*
+ * Does the stack grow up (toward higher addresses) or down
+ * (toward lower addresses)?
+ *
+ * If TRUE, then the grows upward.
+ * If FALSE, then the grows toward smaller addresses.
+ */
+
+#define CPU_STACK_GROWS_UP FALSE
+
+/*
+ * The following is the variable attribute used to force alignment
+ * of critical RTEMS structures. On some processors it may make
+ * sense to have these aligned on tighter boundaries than
+ * the minimum requirements of the compiler in order to have as
+ * much of the critical data area as possible in a cache line.
+ *
+ * The placement of this macro in the declaration of the variables
+ * is based on the syntactically requirements of the GNU C
+ * "__attribute__" extension. For example with GNU C, use
+ * the following to force a structures to a 32 byte boundary.
+ *
+ * __attribute__ ((aligned (32)))
+ *
+ * NOTE: Currently only the Priority Bit Map table uses this feature.
+ * To benefit from using this, the data must be heavily
+ * used so it will stay in the cache and used frequently enough
+ * in the executive to justify turning this on.
+ */
+
+#define CPU_STRUCTURE_ALIGNMENT __attribute__ ((aligned(16)))
+
+/*
+ * Define what is required to specify how the network to host conversion
+ * routines are handled.
+ *
+ * NOTE: SHes can be big or little endian, the default is big endian
+ */
+
+/* __LITTLE_ENDIAN__ is defined if -ml is given to gcc */
+#if defined(__LITTLE_ENDIAN__)
+#define CPU_BIG_ENDIAN FALSE
+#define CPU_LITTLE_ENDIAN TRUE
+#else
+#define CPU_BIG_ENDIAN TRUE
+#define CPU_LITTLE_ENDIAN FALSE
+#endif
+
+/*
+ * The following defines the number of bits actually used in the
+ * interrupt field of the task mode. How those bits map to the
+ * CPU interrupt levels is defined by the routine _CPU_ISR_Set_level().
+ */
+
+#define CPU_MODES_INTERRUPT_MASK 0x0000000f
+
+/*
+ * Processor defined structures required for cpukit/score.
+ */
+
+/* may need to put some structures here. */
+
+/*
+ * Contexts
+ *
+ * Generally there are 2 types of context to save.
+ * 1. Interrupt registers to save
+ * 2. Task level registers to save
+ *
+ * This means we have the following 3 context items:
+ * 1. task level context stuff:: Context_Control
+ * 2. floating point task stuff:: Context_Control_fp
+ * 3. special interrupt level context :: Context_Control_interrupt
+ *
+ * On some processors, it is cost-effective to save only the callee
+ * preserved registers during a task context switch. This means
+ * that the ISR code needs to save those registers which do not
+ * persist across function calls. It is not mandatory to make this
+ * distinctions between the caller/callee saves registers for the
+ * purpose of minimizing context saved during task switch and on interrupts.
+ * If the cost of saving extra registers is minimal, simplicity is the
+ * choice. Save the same context on interrupt entry as for tasks in
+ * this case.
+ *
+ * Additionally, if gdb is to be made aware of RTEMS tasks for this CPU, then
+ * care should be used in designing the context area.
+ *
+ * On some CPUs with hardware floating point support, the Context_Control_fp
+ * structure will not be used or it simply consist of an array of a
+ * fixed number of bytes. This is done when the floating point context
+ * is dumped by a "FP save context" type instruction and the format
+ * is not really defined by the CPU. In this case, there is no need
+ * to figure out the exact format -- only the size. Of course, although
+ * this is enough information for RTEMS, it is probably not enough for
+ * a debugger such as gdb. But that is another problem.
+ */
+
+typedef struct {
+ uint32_t *r15; /* stack pointer */
+
+ uint32_t macl;
+ uint32_t mach;
+ uint32_t *pr;
+
+ uint32_t *r14; /* frame pointer/call saved */
+
+ uint32_t r13; /* call saved */
+ uint32_t r12; /* call saved */
+ uint32_t r11; /* call saved */
+ uint32_t r10; /* call saved */
+ uint32_t r9; /* call saved */
+ uint32_t r8; /* call saved */
+
+ uint32_t *r7; /* arg in */
+ uint32_t *r6; /* arg in */
+
+#if 0
+ uint32_t *r5; /* arg in */
+ uint32_t *r4; /* arg in */
+#endif
+
+ uint32_t *r3; /* scratch */
+ uint32_t *r2; /* scratch */
+ uint32_t *r1; /* scratch */
+
+ uint32_t *r0; /* arg return */
+
+ uint32_t gbr;
+ uint32_t sr;
+
+} Context_Control;
+
+#define _CPU_Context_Get_SP( _context ) \
+ (_context)->r15
+
+typedef struct {
+#if SH_HAS_FPU
+#ifdef SH4_USE_X_REGISTERS
+ union {
+ float f[16];
+ double d[8];
+ } x;
+#endif
+ union {
+ float f[16];
+ double d[8];
+ } r;
+ float fpul; /* fp communication register */
+ uint32_t fpscr; /* fp control register */
+#endif /* SH_HAS_FPU */
+} Context_Control_fp;
+
+typedef struct {
+} CPU_Interrupt_frame;
+
+/*
+ * This variable is optional. It is used on CPUs on which it is difficult
+ * to generate an "uninitialized" FP context. It is filled in by
+ * _CPU_Initialize and copied into the task's FP context area during
+ * _CPU_Context_Initialize.
+ */
+
+#if SH_HAS_FPU
+SCORE_EXTERN Context_Control_fp _CPU_Null_fp_context;
+#endif
+
+/*
+ * Nothing prevents the porter from declaring more CPU specific variables.
+ */
+
+/* XXX: if needed, put more variables here */
+SCORE_EXTERN void CPU_delay( uint32_t microseconds );
+
+/*
+ * The size of the floating point context area. On some CPUs this
+ * will not be a "sizeof" because the format of the floating point
+ * area is not defined -- only the size is. This is usually on
+ * CPUs with a "floating point save context" instruction.
+ */
+
+#define CPU_CONTEXT_FP_SIZE sizeof( Context_Control_fp )
+
+/*
+ * Amount of extra stack (above minimum stack size) required by
+ * MPCI receive server thread. Remember that in a multiprocessor
+ * system this thread must exist and be able to process all directives.
+ */
+
+#define CPU_MPCI_RECEIVE_SERVER_EXTRA_STACK 0
+
+/*
+ * This defines the number of entries in the ISR_Vector_table managed
+ * by RTEMS.
+ */
+
+#define CPU_INTERRUPT_NUMBER_OF_VECTORS 256
+#define CPU_INTERRUPT_MAXIMUM_VECTOR_NUMBER (CPU_INTERRUPT_NUMBER_OF_VECTORS - 1)
+
+/*
+ * This is defined if the port has a special way to report the ISR nesting
+ * level. Most ports maintain the variable _ISR_Nest_level.
+ */
+
+#define CPU_PROVIDES_ISR_IS_IN_PROGRESS FALSE
+
+/*
+ * Should be large enough to run all RTEMS tests. This ensures
+ * that a "reasonable" small application should not have any problems.
+ *
+ * We have been able to run the sptests with this value, but have not
+ * been able to run the tmtest suite.
+ */
+
+#define CPU_STACK_MINIMUM_SIZE 4096
+
+/*
+ * CPU's worst alignment requirement for data types on a byte boundary. This
+ * alignment does not take into account the requirements for the stack.
+ */
+#if defined(__SH4__)
+/* FIXME: sh3 and SH3E? */
+#define CPU_ALIGNMENT 8
+#else
+#define CPU_ALIGNMENT 4
+#endif
+
+/*
+ * This number corresponds to the byte alignment requirement for the
+ * heap handler. This alignment requirement may be stricter than that
+ * for the data types alignment specified by CPU_ALIGNMENT. It is
+ * common for the heap to follow the same alignment requirement as
+ * CPU_ALIGNMENT. If the CPU_ALIGNMENT is strict enough for the heap,
+ * then this should be set to CPU_ALIGNMENT.
+ *
+ * NOTE: This does not have to be a power of 2. It does have to
+ * be greater or equal to than CPU_ALIGNMENT.
+ */
+
+#define CPU_HEAP_ALIGNMENT CPU_ALIGNMENT
+
+/*
+ * This number corresponds to the byte alignment requirement for memory
+ * buffers allocated by the partition manager. This alignment requirement
+ * may be stricter than that for the data types alignment specified by
+ * CPU_ALIGNMENT. It is common for the partition to follow the same
+ * alignment requirement as CPU_ALIGNMENT. If the CPU_ALIGNMENT is strict
+ * enough for the partition, then this should be set to CPU_ALIGNMENT.
+ *
+ * NOTE: This does not have to be a power of 2. It does have to
+ * be greater or equal to than CPU_ALIGNMENT.
+ */
+
+#define CPU_PARTITION_ALIGNMENT CPU_ALIGNMENT
+
+/*
+ * This number corresponds to the byte alignment requirement for the
+ * stack. This alignment requirement may be stricter than that for the
+ * data types alignment specified by CPU_ALIGNMENT. If the CPU_ALIGNMENT
+ * is strict enough for the stack, then this should be set to 0.
+ *
+ * NOTE: This must be a power of 2 either 0 or greater than CPU_ALIGNMENT.
+ */
+
+#define CPU_STACK_ALIGNMENT CPU_ALIGNMENT
+
+/*
+ * ISR handler macros
+ */
+
+/*
+ * Support routine to initialize the RTEMS vector table after it is allocated.
+ *
+ * SH Specific Information: NONE
+ */
+
+#define _CPU_Initialize_vectors()
+
+/*
+ * Disable all interrupts for an RTEMS critical section. The previous
+ * level is returned in _level.
+ */
+
+#define _CPU_ISR_Disable( _level) \
+ sh_disable_interrupts( _level )
+
+/*
+ * Enable interrupts to the previous level (returned by _CPU_ISR_Disable).
+ * This indicates the end of an RTEMS critical section. The parameter
+ * _level is not modified.
+ */
+
+#define _CPU_ISR_Enable( _level) \
+ sh_enable_interrupts( _level)
+
+/*
+ * This temporarily restores the interrupt to _level before immediately
+ * disabling them again. This is used to divide long RTEMS critical
+ * sections into two or more parts. The parameter _level is not
+ * modified.
+ */
+
+#define _CPU_ISR_Flash( _level) \
+ sh_flash_interrupts( _level)
+
+/*
+ * Map interrupt level in task mode onto the hardware that the CPU
+ * actually provides. Currently, interrupt levels which do not
+ * map onto the CPU in a generic fashion are undefined. Someday,
+ * it would be nice if these were "mapped" by the application
+ * via a callout. For example, m68k has 8 levels 0 - 7, levels
+ * 8 - 255 would be available for bsp/application specific meaning.
+ * This could be used to manage a programmable interrupt controller
+ * via the rtems_task_mode directive.
+ */
+
+#define _CPU_ISR_Set_level( _newlevel) \
+ sh_set_interrupt_level(_newlevel)
+
+uint32_t _CPU_ISR_Get_level( void );
+
+/* end of ISR handler macros */
+
+/* Context handler macros */
+
+/*
+ * Initialize the context to a state suitable for starting a
+ * task after a context restore operation. Generally, this
+ * involves:
+ *
+ * - setting a starting address
+ * - preparing the stack
+ * - preparing the stack and frame pointers
+ * - setting the proper interrupt level in the context
+ * - initializing the floating point context
+ *
+ * This routine generally does not set any unnecessary register
+ * in the context. The state of the "general data" registers is
+ * undefined at task start time.
+ *
+ * NOTE: This is_fp parameter is TRUE if the thread is to be a floating
+ * point thread. This is typically only used on CPUs where the
+ * FPU may be easily disabled by software such as on the SPARC
+ * where the PSR contains an enable FPU bit.
+ */
+
+/*
+ * FIXME: defined as a function for debugging - should be a macro
+ */
+SCORE_EXTERN void _CPU_Context_Initialize(
+ Context_Control *_the_context,
+ void *_stack_base,
+ uint32_t _size,
+ uint32_t _isr,
+ void (*_entry_point)(void),
+ int _is_fp );
+
+/*
+ * This routine is responsible for somehow restarting the currently
+ * executing task. If you are lucky, then all that is necessary
+ * is restoring the context. Otherwise, there will need to be
+ * a special assembly routine which does something special in this
+ * case. Context_Restore should work most of the time. It will
+ * not work if restarting self conflicts with the stack frame
+ * assumptions of restoring a context.
+ */
+
+#define _CPU_Context_Restart_self( _the_context ) \
+ _CPU_Context_restore( (_the_context) );
+
+/*
+ * The purpose of this macro is to allow the initial pointer into
+ * a floating point context area (used to save the floating point
+ * context) to be at an arbitrary place in the floating point
+ * context area.
+ *
+ * This is necessary because some FP units are designed to have
+ * their context saved as a stack which grows into lower addresses.
+ * Other FP units can be saved by simply moving registers into offsets
+ * from the base of the context area. Finally some FP units provide
+ * a "dump context" instruction which could fill in from high to low
+ * or low to high based on the whim of the CPU designers.
+ */
+
+#define _CPU_Context_Fp_start( _base, _offset ) \
+ ( (void *) _Addresses_Add_offset( (_base), (_offset) ) )
+
+/*
+ * This routine initializes the FP context area passed to it to.
+ * There are a few standard ways in which to initialize the
+ * floating point context. The code included for this macro assumes
+ * that this is a CPU in which a "initial" FP context was saved into
+ * _CPU_Null_fp_context and it simply copies it to the destination
+ * context passed to it.
+ *
+ * Other models include (1) not doing anything, and (2) putting
+ * a "null FP status word" in the correct place in the FP context.
+ * SH1, SH2, SH3 have no FPU, but the SH3e and SH4 have.
+ */
+
+#if SH_HAS_FPU
+#define _CPU_Context_Initialize_fp( _destination ) \
+ do { \
+ *(*(_destination)) = _CPU_Null_fp_context;\
+ } while(0)
+#else
+#define _CPU_Context_Initialize_fp( _destination ) \
+ { }
+#endif
+
+/* end of Context handler macros */
+
+/* Fatal Error manager macros */
+
+/*
+ * FIXME: Trap32 ???
+ *
+ * This routine copies _error into a known place -- typically a stack
+ * location or a register, optionally disables interrupts, and
+ * invokes a Trap32 Instruction which returns to the breakpoint
+ * routine of cmon.
+ */
+
+#ifdef BSP_FATAL_HALT
+ /* we manage the fatal error in the board support package */
+ void bsp_fatal_halt( uint32_t _error);
+#define _CPU_Fatal_halt( _error ) bsp_fatal_halt( _error)
+#else
+#define _CPU_Fatal_halt( _error)\
+{ \
+ __asm__ volatile("mov.l %0,r0"::"m" (_error)); \
+ __asm__ volatile("mov #1, r4"); \
+ __asm__ volatile("trapa #34"); \
+}
+#endif
+
+/* end of Fatal Error manager macros */
+
+/* Bitfield handler macros */
+
+/*
+ * This routine sets _output to the bit number of the first bit
+ * set in _value. _value is of CPU dependent type Priority_bit_map_Control.
+ * This type may be either 16 or 32 bits wide although only the 16
+ * least significant bits will be used.
+ *
+ * There are a number of variables in using a "find first bit" type
+ * instruction.
+ *
+ * (1) What happens when run on a value of zero?
+ * (2) Bits may be numbered from MSB to LSB or vice-versa.
+ * (3) The numbering may be zero or one based.
+ * (4) The "find first bit" instruction may search from MSB or LSB.
+ *
+ * RTEMS guarantees that (1) will never happen so it is not a concern.
+ * (2),(3), (4) are handled by the macros _CPU_Priority_mask() and
+ * _CPU_Priority_bits_index(). These three form a set of routines
+ * which must logically operate together. Bits in the _value are
+ * set and cleared based on masks built by _CPU_Priority_mask().
+ * The basic major and minor values calculated by _Priority_Major()
+ * and _Priority_Minor() are "massaged" by _CPU_Priority_bits_index()
+ * to properly range between the values returned by the "find first bit"
+ * instruction. This makes it possible for _Priority_Get_highest() to
+ * calculate the major and directly index into the minor table.
+ * This mapping is necessary to ensure that 0 (a high priority major/minor)
+ * is the first bit found.
+ *
+ * This entire "find first bit" and mapping process depends heavily
+ * on the manner in which a priority is broken into a major and minor
+ * components with the major being the 4 MSB of a priority and minor
+ * the 4 LSB. Thus (0 << 4) + 0 corresponds to priority 0 -- the highest
+ * priority. And (15 << 4) + 14 corresponds to priority 254 -- the next
+ * to the lowest priority.
+ *
+ * If your CPU does not have a "find first bit" instruction, then
+ * there are ways to make do without it. Here are a handful of ways
+ * to implement this in software:
+ *
+ * - a series of 16 bit test instructions
+ * - a "binary search using if's"
+ * - _number = 0
+ * if _value > 0x00ff
+ * _value >>=8
+ * _number = 8;
+ *
+ * if _value > 0x0000f
+ * _value >=8
+ * _number += 4
+ *
+ * _number += bit_set_table[ _value ]
+ *
+ * where bit_set_table[ 16 ] has values which indicate the first
+ * bit set
+ */
+
+#define CPU_USE_GENERIC_BITFIELD_CODE TRUE
+#define CPU_USE_GENERIC_BITFIELD_DATA TRUE
+
+#if (CPU_USE_GENERIC_BITFIELD_CODE == FALSE)
+
+extern uint8_t _bit_set_table[];
+
+#define _CPU_Bitfield_Find_first_bit( _value, _output ) \
+ { \
+ _output = 0;\
+ if(_value > 0x00ff) \
+ { _value >>= 8; _output = 8; } \
+ if(_value > 0x000f) \
+ { _output += 4; _value >>= 4; } \
+ _output += _bit_set_table[ _value]; }
+
+#endif
+
+/* end of Bitfield handler macros */
+
+/*
+ * This routine builds the mask which corresponds to the bit fields
+ * as searched by _CPU_Bitfield_Find_first_bit(). See the discussion
+ * for that routine.
+ */
+
+#if (CPU_USE_GENERIC_BITFIELD_CODE == FALSE)
+
+#define _CPU_Priority_Mask( _bit_number ) \
+ ( 1 << (_bit_number) )
+
+#endif
+
+/*
+ * This routine translates the bit numbers returned by
+ * _CPU_Bitfield_Find_first_bit() into something suitable for use as
+ * a major or minor component of a priority. See the discussion
+ * for that routine.
+ */
+
+#if (CPU_USE_GENERIC_BITFIELD_CODE == FALSE)
+
+#define _CPU_Priority_bits_index( _priority ) \
+ (_priority)
+
+#endif
+
+/* end of Priority handler macros */
+
+/* functions */
+
+/*
+ * _CPU_Initialize
+ *
+ * This routine performs CPU dependent initialization.
+ */
+
+void _CPU_Initialize(void);
+
+/*
+ * _CPU_ISR_install_raw_handler
+ *
+ * This routine installs a "raw" interrupt handler directly into the
+ * processor's vector table.
+ */
+
+void _CPU_ISR_install_raw_handler(
+ uint32_t vector,
+ proc_ptr new_handler,
+ proc_ptr *old_handler
+);
+
+/*
+ * _CPU_ISR_install_vector
+ *
+ * This routine installs an interrupt vector.
+ */
+
+void _CPU_ISR_install_vector(
+ uint32_t vector,
+ proc_ptr new_handler,
+ proc_ptr *old_handler
+);
+
+/*
+ * _CPU_Install_interrupt_stack
+ *
+ * This routine installs the hardware interrupt stack pointer.
+ *
+ * NOTE: It needs only be provided if CPU_HAS_HARDWARE_INTERRUPT_STACK
+ * is TRUE.
+ */
+
+void _CPU_Install_interrupt_stack( void );
+
+/*
+ * _CPU_Thread_Idle_body
+ *
+ * This routine is the CPU dependent IDLE thread body.
+ *
+ * NOTE: It need only be provided if CPU_PROVIDES_IDLE_THREAD_BODY
+ * is TRUE.
+ */
+
+void *_CPU_Thread_Idle_body( uintptr_t ignored );
+
+/*
+ * _CPU_Context_switch
+ *
+ * This routine switches from the run context to the heir context.
+ */
+
+void _CPU_Context_switch(
+ Context_Control *run,
+ Context_Control *heir
+);
+
+/*
+ * _CPU_Context_restore
+ *
+ * This routine is generally used only to restart self in an
+ * efficient manner. It may simply be a label in _CPU_Context_switch.
+ */
+
+void _CPU_Context_restore(
+ Context_Control *new_context
+) RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
+
+/*
+ * _CPU_Context_save_fp
+ *
+ * This routine saves the floating point context passed to it.
+ */
+
+void _CPU_Context_save_fp(
+ Context_Control_fp **fp_context_ptr
+);
+
+/*
+ * _CPU_Context_restore_fp
+ *
+ * This routine restores the floating point context passed to it.
+ */
+
+void _CPU_Context_restore_fp(
+ Context_Control_fp **fp_context_ptr
+);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif